Aliasing vs Anti-aliasing
ALIASING
Definition
Aliasing can be defined in different terms like physics and computing.
- In physics it is defined as the misidentification of a signal frequency, introducing distortion or error.
- In computing it is defined as the distortion of a reproduced image so that curved or inclined lines appear inappropriately jagged,
Description
- For images, this produces a jagged edge,or stair-step effect.
- For sound,it produces a buzz( a low and continuous hamming).
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| Aliasing |
- Aliasing is the visual stair-stepping of edges that occurs in an image when the resolution is too low.
- In signal processing and related disciplines, aliasing is an effect that causes different signals to become indistinguishable when sample.
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| Aliasing in signals |
Types of aliasing
There are two types of aliasing: spatial and temporal.- Spatial aliasing means insufficient sampling of the data along the space axis. This difficulty is so universal, that all migration methods must consider it.
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| Spatial aliasing |
- Temporal aliasing is caused by the sampling rate (i.e. number of frames per second) of a scene being too low compared to the transformation speed of objects inside of the scene.
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| Temporal aliasing |
ANTI-ALIASING
Definition
- Anti-aliasing is the smoothing of the image or sound roughness caused by aliasing.
- Anti-aliasing may refer to any of a number of techniques to combat the problems of aliasing in a sampled signal such as a digital image or digital audio recording.
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| Anti-aliasing |
Description
- With images, approaches include adjusting pixel positions or setting pixel intensities.
- With sound, aliases are removed by eliminating frequencies above half the sampling frequencies.
- In computer graphics, anti-aliasing is a software technique for diminishing jaggies - stair-step-like lines that should be smooth.
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| Anti-aliased object |
What does Anti-aliasing do?
- Anti-aliasing makes these curved or slanting lines smooth again by adding a slight discoloration to the edges of the line or object, causing the jagged edges to blur and melt together.
Types of anti-aliasing
There are mainly two anti-aliasing techniques: spatial and temporal.- Spatial anti-aliasing is a the technique of minimizing aliasing when representing a high-resolution image at a lower resolution. Below are sub types in spatial anti-aliasing.
Multi-sample Anti-aliasing
Adaptive Anti-aliasing:
Coverage Sampling Anti-aliasing
Enhanced Quality Anti-aliasing
Fast Approximate Anti-aliasing
Temporal Anti-aliasing
- Temporal aliasing is a technique used to control the effects of temporal aliasing.
Examples of aliasing vs anti-aliasing
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| Example 01 |
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| Example 02 |